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Brock said:I am sure Ikendu will pop in here soon /ubbthreads/images/graemlins/wink.gif
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You have stroked theee lamp and I respond to your summons... what knowledge may I supply at your bidding? >appears from glowing puff of smoke< /ubbthreads/images/graemlins/grin.gif
Yes. This is one of those few areas that I really know something about.
We are talking about home brew biodiesel.
I helped start a "club" in my area for guys wanting to home brew their own biodiesel. Two of the guys had already been making small amounts in (literally) a 5-gallon bucket (not the best practice BTW).
The ingrediants cost about 45 cents per gallon for lye and methanol. The club doles out home brew to its members for about $1 dues per 1 gallon of home brew biodiesel. The extra dues go for capital improvements to the processor and other facilities.
The basic chemistry is simple:
1. Find a restaurant to donate used fryer oil
Most restaurants pay anywhere from 15-90 cents/gal to have their used grease (mostly oil from the fryers) hauled away by a "renderer". These companies take the used grease and turn it into pet food and other products. So... haven't seen a restaurant yet that wasn't happy to give it away to someone else at no charge. Big chains like McDonalds or Burger King don't usually work because the local mgmt doesn't have the authority to do something different.
2. Strain out the bits of food, etc.
3. Mix up some reactant
The basic chemistry going on is to make the vegetable oil "thinner" so it will flow like diesel fuel through the fuel injectors. You do this by removing the glycerin molecule from the oil. Glycerin is the thick stuff that hand soaps or shampoos are made of.
The glycerin is broken off by the use of a strong "base" (lye). Most people use sodium hydroxide (like Red Devil lye for clearing drains). The club I know likes to use potassium hydroxide.
The remaining hydrocarbon chains from the vegetable oil want to re-join with something...so you mix in an alcohol to bind it all up into a fuel which is very much like diesel fuel in its properties. Most people use methanol for the alcohol (made from natural gas) but you can use ethanol (they do in Europe). Using ethanol makes a superior cold weather form of biodiesel but the reaction is trickier for home brewers to get right using ethanol.
If you pre-mix lye and methanol, you get what we call methoxide. BTW...in this early stage, you are dealing with some fairly bad chemicals. The lye can eat through your skin and the methanol can cause blindness or even be fatal if absorbed thru the skin...so you have to be pretty careful when mixing or pouring these chemicals. You don't want to breathe methanol or methoxide fumes.
Still...we handle Red Devil lye all the time in our society and methanol is what model airplane folks use for their fuel (also used for racing fuel). You just need to be careful at this stage.
4. Warm up the oil
The reaction goes most completely and quickly at about 130F.
5. Mix in the reactants
The club I know of uses an electric water heater for a reaction vessel and a small pump to circulate the oil, lye and methanol so they are well mixed. The guys that were making it in 5-gallon buckets had a drill with a long shank poked thru the closed lid of the bucket to mix the oil. Doing it this way with a bucket allows too much opportunity to breathe methanol fumes and splash nasty chemicals IMHO. But...they did it that way for a while with no adverse effects.
6. Let it sit 24 hours.
The glycerin needs to settle out of the mixture (it is heavier then the biodiesel) so most people just walk away after mixing and let it sit overnight. The next morning, they open a valve at the bottom of the reaction vessel (water heater) and drain off the dark liquid. Some people use the gylcerin as a shop degreaser and you can burn it at high temperatures (like a shop waste oil burner). Some simply hand it over to the waste handling agency in their area. I suppose some of that stuff ends up in a landfill...which is where some of the waste oil would have ended up anyway, only now the volume has been reduced by about 80%.
7. "Washing"
The remaining biodiesel may contain some unused lye, unreacted methanol and/or glycerin that didn't quite settle out yet. The best biodiesel doesn't contain any of these things so... some people (most I think) "wash" the home brew biodiesel before they use it.
This is a delicate stage 'cause if you agitate the mixture, any glycerin that is still in the mix could make the whole thing quite "soapy" and take forever to settle out after that. So people do a "mist wash". They pump the biodiesel into an open 55 gallon drum and then gently mist water over the surface. The mist settles down through the oil (oil is lighter than water) and collects any leftovers along the way. A 55 gallon batch might have a couple of gallons of water misted as a wash.
You let this settle overnight again, and drain off the water from the bottom (or pull the biodiesel off of the top). The very best home brew biodiesel is like wine... you let it sit for a while before consuming, this gives anything else a chance to settle out (glycerin, water, whatever) before you use it.
So... how much time does all of this take?
The big time consumers are:
1. Collecting the oil
2. Mixing the first batch
3. Draining and washing
Most of the elapsed time is simply letting it sit.
I've heard home brew biodiesel compared to heating your house with wood; finding, cutting, splitting, letting it season, etc. That's probably not too far off.
The guys in our local club (about 5 members) share the duties and pitch in dues to pay for the ingrediants and improvements to the processor. In the end, they pay about $1/gal for their fuel. I'm paying $2.60/gal for manufactured biodiesel right now.
Is it worth it? They think so. It's not for everyone. They "brew" once/week and make a kind of party out of it.
BTW...the finished biodiesel is extremely safe to store and transport as a fuel. The flash point (the temp at which a fuel will self-volatize and ignite in the presence of a spark or a flame) for fuels we use is as follows:
Gasoline:........-45F <--- Wow! Dangerous stuff!! (anyone remember exploding Pinto gas tanks?)
Diesel fuel:...+125F <--- Much, much safer
BioDiesel:.....+300F <--- Very, very safe.
There's more on BioDiesel at my web site:
itsgood4.us
